Gray matter volume in major depressive disorder: a meta-analysis of voxel-based morphometry studies.

We designed this study to perform a meta-analysis of gray matter (GM) findings in major depressive disorder (MDD) by using the signed differential mapping (SDM) toolbox. The Pubmed, ScienceDirect and Scopus databases were searched, and only studies published or published online before November 2010 have been included. Twenty voxel-based morphometry (VBM) studies of adult MDD patients were entered in the meta-analysis by SDM toolbox with threshold criteria set as error probability less than 0.00005 and cluster more than 50 voxels. Onset age, numbers of patients and controls, gender ratio of both groups, ratio of medicated patients, depression rating scores, illness duration, co-morbidity and existence of corrected p value were also meta-regressed as covariates to exclude confounding biases. Voxel-wise meta-analytic results of these 20 VBM studies in MDD patients revealed that GM deficits were observed in the right anterior cingulate cortex and left anterior cingulate cortex when patients were compared with controls. The findings remained mostly unchanged in jackknife sensitivity analyses. The potential confounding factors had little impact on the results. This meta-analysis suggested GM deficits of the anterior cingulate cortex might be important in the etiology of MDD.